This invention relates to sheet feeding apparatuses wherein a sheet is buckled during feeding. Devices are provided for assisting in the flattening of the buckle during continued sheet feeding. Reproducing machines employing sheet feeding apparatuses as above noted are also provided.
It is quite conventional in the sheet feeding art to buckle a sheet in order to separate it from a stack of sheets or to align it for purposes of registration. When a sheet feeder is used in a compact environment or when the buckle forming device includes closely spaced constraints on the buckle, it has been found that difficulties arise when one attempts to feed the sheet following buckle formation since the sheet may hang up against the buckle constraints. Therefore, merely removing a stop, for example, will not necessarily cause the sheet to snap forward and the buckle to flatten out.
U.S. Pat. Nos. 1,225,740, 2,151,073, and 2,912,240 are exemplary of sheet feeding apparatuses wherein a buckle is formed between a sheet feeding means and a constraining member.
U.S. Pat. No. 3,279,787 shows the formation of a buckle in a reverse buckle type sheet feeding apparatus wherein a lever actuated switch engages the buckle as it is formed in order to limit the height of the buckle formed. It is not apparent whether the force exerted by the lever actuator on the buckle would be effective to assist in flattening the buckle during forward feeding. It would probably not be an effective flattening device since the lever contacts the buckle at a single location.
In U.S. Pat. No. 2,289,502, an air blast from an orifice is utilized to assist in flattening a buckle to enhance sheet feeding.
In U.S. Pat. Nos. 672,529; 2,246,508; 3,015,485; 3,281,144, and 3,517,923, pivoting registration gates are shown. In U.S. Pat. No. 3,298,682, a specific pivoting registration gate is shown which is suspended above the sheet. The registration gate of this patent includes a surface having a very limited extent in the transverse direction connected to the registration tales.
In U.S. Pat. No. 3,768,803, a friction retard separator of unique design which is particularly adapted for use in the sheet feeding apparatus of this invention is described. This separator has proved to be a highly reliable means for feeding individual sheets one at a time from a stack. It is disclosed to be useful with both top feeders and bottom feeders. A wide variety of approaches to mounting the separator are described including a pivotal mounting which allows the separator to pivot against the stack as the stack depletes. In the disclosed separator a feed belt is supported for movement about a pair of pulleys. A curved retard means is positioned against the section of the belt between the pulleys to form a sheet queing throat. The belt contacts the stack near the edge and the throat acts to que or align the sheets for advancement into a sheet handling system.